Method for producing a grating image grating image and security document

ABSTRACT

To produce a grating image for a security document it is disclosed to fill a contour line ( 9 ) with hatching lines ( 11 ) with the help of a drawing program, to calculate grating coordinates from the intersection points, the hatching lines ( 11 ) have with the contour line ( 9 ), and to supply the such produced data records to a lithography machine.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Phase of International Application SerialNo. PCT/EP03/06081, filed Jun. 10, 2003.

FIELD OF THE INVENTION

The invention relates to a method for producing a grating image having agrating pattern, the grating pattern being formed on the surface of asubstrate with the aid of a writing apparatus.

DESCRIPTION OF THE BACKGROUND ART

The invention further relates to a grating image and a securitydocument, such as bank notes, ID cards, or the like, with such a gratingimage.

Holograms, holographic grating images and further optically variablediffraction structures are used as security elements against forgeriesin credit cards, bank notes, product packaging and the like. In generalthe manufacturing of these diffraction structures begins with exposing alight-sensitive layer to overlapping, coherent light beams.

Real holograms are formed by illuminating an object with coherent laserlight, the laser light disturbed by the object being overlapped with anundisturbed reference beam in the light-sensitive layer.

Holographic diffraction gratings are the result, when the light beamsoverlapping in the light-sensitive layer consist of spatially expanded,uniform, coherent wave fields. When these are allowed to act upon thelight-sensitive layer, e.g. a photographic film or a photoresist layer,the result is a holographic diffraction grating, which e.g. in aphotographic film is preserved as bright and dark lines or in aphotoresist layer as peaks and valleys. Because the light beams in thiscase are not disturbed by an object, the only result is an opticallyvariable colour effect, but not the display of an image.

Holographic grating images can be produced out of holographicdiffraction gratings, when not the entire surface of the light-sensitivematerial is covered with a uniform holographic diffraction grating, butmasks are used, so that only parts of the recording area are coveredwith a uniform grating pattern, while other parts of the recording areamay be covered with other grating patterns with the help of other masks.A holographic grating image thus is composed of several grating fieldswith different diffraction grating patterns. With a grating image formedout of the sum of the grating fields most different image motifs can bedepicted.

The diffraction gratings of a holographic grating image, usually, areruled gratings with a multitude of grating lines located side by side.All diffraction gratings of each grating field or image field of thegrating image are characterized by the grating constant, the azimuthangle and the contour or the outline. The grating constant herecorresponds to the distance between the grating lines and the azimuthangle describes the inclination of the grating lines with respect to areference direction. The grating constant and the azimuth angle aredetermined by the wavelength and the incidence direction of the wavefields used for exposing. The outlines of the image fields are producedwith the aid of masks.

The grating constants of the grating patterns in the individual imagefields are essential for the colours in the grating image, while theazimuth angles of the grating patterns are responsible for thevisibility of these image fields from certain viewing angles. On thebasis of this technique thus optically variable images, e.g. movingimages or also plastically appearing images can be produced.

In general terms there can be stated, that a real hologram is anoverlapping of holographic diffraction gratings, whereas in aholographic grating image several holographic diffraction gratings aredisposed side by side. In general, real holograms appearphotographically true-to-life compared to grating images. Gratingimages, however, can be designed graphically. In addition, gratingimages are more light intensive than real holograms, since theundisturbed diffraction gratings located side by side shine moreintensive than the overlapping disturbed diffraction gratings.

The diffraction gratings located side by side can be holographicallyproduced in different ways. One possibility is to divide the gratingimage into large-surface image fields and develop covering masks forthese, which permit only one image field to be exposed at a time to forma uniform holographic diffraction grating. Or the entire grating imageis divided into a multitude of small, nearly dot-shaped areas, these dotareas having a diameter of 10 to 200 micrometer. In the dot areas thenwith the aid of a dot matrix machine holographic diffraction gratingscan be formed.

In particular with finely structured grating fields with differentgrating data the mask method is cumbersome in handling. Since the maskshave to be brought into very close contact with the light-sensitivelayer during the exposure process and positioned very precisely, whichrequires manual skill and dexterity.

But the manufacturing of the grating images divided into dot areascauses problems as well. The grating images divided into dot areas infact can be produced automatically by machine and without requiringmanual skill, but then the intensity of the reflected light is reducedby the spacings between the dot areas. Furthermore, the colours of thereflected light are distorted, since the gratings are composed in asmall-surface fashion and are not uniform over a large surface. Furtherdisadvantages are the perceptibility of the divided dots when viewedunder a magnifying glass as well as the low degree of security, becausedot matrix machines are easily available.

Furthermore, it is known to produce the dot areas of a quasi-screenedgrating image by means of an electron beam. The aforementioneddisadvantages in connection with the grating image being divided intodots, however, apply in the same way also to this manufacturing variant.

SUMMARY OF THE INVENTION

Starting out from this prior art it is the problem of the invention toprovide a method for producing grating images, which leads to opticallyvariable grating images of a high light intensity, for the manufacturerof grating images is reliably realizable, and complicates the access forimitators by not dividing the grating images into dot areas.

Furthermore, it is the problem of the invention to create an opticallyvariable grating image, which is easy to produce, and a securitydocument with such a grating image.

This problem is solved by a method, a grating image, and a securityelement having the features disclosed herein. Also specified areadvantageous embodiments and developments of the invention.

The invention enables large surfaces, visible to the naked eye, to becovered with a uniform grating, namely in a simple, non-holographicfashion, e.g. by means of a focussed radiation, in particular anelectron beam. I.e., a motif to be depicted is divided into individualimage fields, which have an extent visually perceptible and these imagefields are covered with a uniform grating. In this way the lightintensity of the grating image can be increased, since unexposedspacings do not exist. The distortion of colours is also prevented,because the fields are covered over a large area with a grating and arenot composed of small-surfaced dots with interfering spacings.

With this method at first the contour lines of the grating fields thegrating image consists of are determined, and then the contour lines orthe grating fields are filled with the desired grating pattern. In thesimplest case a grating image consists of one single grating field,which has a contour line corresponding to that of the motif to bedepicted. The components of the grating pattern within the contour linethen are described by grating coordinates, which are supplied to awriting apparatus. The writing apparatus is an apparatus, whichpreferably by means of a suitable radiation, in particular a bundledbeam, on the basis of the grating coordinates causes a change of statein a radiation-sensitive substrate material, so as to produce thegrating fields of a grating image in the substrate.

The method according to the invention is particularly suitable for theautomatic machine production of large-surface grating fields, sincecontour lines for the grating fields can be prepared and filled withgrating patterns with the aid of computer programs. Computer programsare also able to output grating coordinates suitable for describing thegrating patterns to an apparatus for processing the radiation-sensitivematerial. Once a process according to the invention is set up, themanufacturer is in a position to repeatedly perform the method in areliable fashion. The access for imitators, however, is made moredifficult, since the apparatuses implementing the inventive method arenot available on the market in this combination by standard and are veryexpensive.

It is to be further emphasized, that with this inventive methodlight-intensive grating images can be produced, because the methodpermits the production of grating fields of nearly any size.

In one preferred embodiment the grating pattern is a ruled grating, theintersection points the grating lines have with the contour linerespectively defining starting point and end point of the respectivegrating line, the coordinates of which are supplied to the writingapparatus for processing the light-sensitive material.

The inventive proceeding permits a structured storing of the producedgrating coordinates, which, if required, can be transferred to thewriting apparatus.

The grating coordinates, furthermore, preferably are disposed in such away in the file, that the coordinates of the starting point of a gratingline are located side by side with the coordinates of the starting pointof a neighboring grating line and the coordinates of an end point of agrating line are located side by side with the coordinates of the endpoint of a neighboring grating line. Such a disposition of the gratingcoordinates is of advantage, because when working through the gratingcoordinates sorted in such a way the beam follows a meandering linewithout having to cover long idle distances.

Furthermore it is of advantage, when the starting points and end pointsof neighboring grating lines each are connected by reversing distances,so that the beam does not have to cover idle distances between thegrating lines either. In this case the beam does not need to be turnedoff between the grating lines.

For further increasing the writing speed of the beam, the reversingdistances can also be formed in a rounded fashion.

The invention, however, is not restricted to the use of ruled gratingsas grating pattern. Instead of straight grating lines also curved,wave-shaped or any other not straight grating patterns can be used. Inthis case it is not sufficient to store only the coordinates of theintersection points, the grating lines forming the grating pattern havewith the contour line, as starting points and end points. Furthermore,information about the path of the grating lines within the contour linehas to be provided. For that purpose the coordinates of any number ofintermediate points can be used, which as a polygonal curve describe theform of the grating line Alternatively, the form of the grating line canalso be described as a Bezier curve, in which the coordinates of merelya few intermediate points and additionally a tangential direction withrespect to the further path of the curve are stored.

The electron beam being used as a lithography instrument permits veryfine resolutions, even as fine as in the nanometer range. For thatreason it is inventively preferred. In those cases, in which gratingpatterns are to be written without requiring such a high resolution,also other lithography instruments are possible, so as to incorporatethe inventive grating lines into a substrate. This can be, for example,mechanical engraving with a precision milling apparatus or a focussed UVlaser. According to the invention all lithography instruments can beused which permit a drawing of strokes or lines according to thedescribed data records, which from a starting point to an end point eachis written in a sufficiently fine line thickness onto a suitablesubstrate.

The inventive grating images can be transferred to embossing dies of anydesired form, which then are used for embossing any embossable layer,such as for example a thermoplastic layer or a lacquer layer, inparticular a UV curable lacquer layer. This embossable layer preferablyis located on a carrier, such as a plastic foil. Depending on theintended use of the plastic foil, the latter can have additional layersor security features. Thus the foil can be employed as security threador security label. Alternatively, the foil can be designed as a transfermaterial, such as for example in the form of a hot stamping foil, whichserves for the transfer of individual security elements to the objectsto be secured.

The inventive grating images preferably are used for protectingdocuments of value, such as bank notes, ID cards, passports, and thelike. Of course they can be also employed for other goods to be secured,such as CDs, books, etc.

According to the invention it is not necessarily required to compose theentire grating image out of inventive grating fields. In fact also onlyparts of a whole image can be realized in the form of the inventivegrating fields, while other image parts are designed with the help ofother methods, such as for example holographic gratings or realholograms or simple prints.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention is explained in detail with reference tothe accompanying figures. It is pointed out, that the Figures are not atrue-to-scale representation of the invention, but merely serve forillustrating.

FIG. 1 shows a simple grating image with rhomboidal outline;

FIG. 2 shows a grating image composed of large-surface grating fields;

FIG. 3 shows a detail B from the grating image according to FIG. 2,which was manufactured with the help of the dot matrix method accordingto prior art;

FIG. 4 shows an outline of an inventive grating field;

FIG. 5 shows a grating pattern, with which the outline from FIG. 4 is tobe filled;

FIG. 6 shows an overlapping of the grating pattern from FIG. 5 with thecontour line from FIG. 4;

FIG. 7 shows a grating field, the grating lines of which are describedby starting points and end points;

FIG. 8 shows a processing path for the grating field from FIG. 7;

FIG. 9 shows a final grating image;

FIG. 10 shows a further modified processing path for the grating fieldfrom FIG. 7;

FIG. 11 shows the processing path from FIG. 8 without idle distancesbetween neighboring grating lines;

FIG. 12 shows another further modified processing path without idledistances between neighboring grating lines;

FIG. 13 shows the overlapping of a wavy-line-shaped grating pattern withthe contour line from FIG. 4; and

FIG. 14 shows a grating field, the grating lines of which are describedby starting points and end points as well as intermediate points.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 a grating image 1 is shown, which consists of a singlerhomboidal grating field 2. The grating field 2 is filled with a gratingpattern, which has a multitude of grating lines 3 disposed side by side,which are disposed in a distance a to each other. The distance a is alsoreferred to as grating constant. In addition the grating lines 3 arepositioned in an azimuth angle α to a reference direction 4. The gratingconstant is of essential importance for the colour of the grating field,while the azimuth angle α is responsible for the visibility of thegrating field 2 in certain viewing angles.

In FIG. 2 a further grating image 5 is shown, which is composed of amultitude of grating fields 6, 61, 62, 63, 64, 65, 66. Directly adjacentgrating fields differ at least in one grating parameter from each other,such as e.g. the grating constant a or the azimuth angle α, which in theFigure is illustrated by the different hatchings. Not directly adjacentgrating fields can perfectly well be covered with the same gratingpatterns. These grating fields when viewed from the same viewing angleare visually recognizable with the same colour. In the shown examplethis is the case for the grating fields 62, which depict the eyes of theface. For that reason they are covered with the same hatching.

Grating images, such as the grating image 5 shown in FIG. 2, accordingto prior art are produced with the aid of masks and a holographicexposure technique, namely by overlapping spatially expanded, uniformlycoherent wave fields in a light-sensitive layer. Here only those gratingfields are exposed, which have the same grating constant a and the sameazimuth angle α.

If for producing the grating image 5 the known dot matrix method isused, each grating field 6, 61, 62, 63, 64, 65, 66 will be composed of amultitude of dot areas 8, as shown in FIG. 3. In FIG. 3 area B from FIG.2 is shown in a highly magnified fashion, in case the grating image 5was produced with the help of the dot matrix method. The border betweentwo grating fields 64, 65 is shown, which are covered with differentgrating patterns 7, 7′, so as to produce different visual impressions.Here, however, not the entire area of a grating field 64, 65 is providedwith the respective grating pattern 7, 7′, but merely the dot areas 8.The grating patterns 7, 7′ disposed in the dot areas 8 are producedeither with the help of a holographic method namely by the overlappingof coherent wave fields or they are written with electron beam. Thesedot areas 8 are separated from each other by non-diffractingintermediate areas. As already mentioned above these intermediate areaslead to a reduction of the light intensity, i.e. the grating field orthe grating image appears less brilliantly. If the dot areas are placeddirectly next to each other, they will have to be disposed in anoverlapping fashion due to the process tolerances. This overlapping aswell leads to visible perturbing effects, such as distorted colours.

According to the invention each of the grating fields 6, 61, 62, 63, 64,65, 66 of the grating image 5 uniformly within itself is covered with acontinuous grating pattern, which is produced with the aid of acontrollable light beam or particle beam, in particular an electronbeam.

In the following the method for producing the inventive grating fields6, 61, 62, 63, 64, 65, 66 is explained.

According to FIG. 4 in a first procedure step a contour line 9 iscreated, which corresponds to the contour line of the future gratingfield 6, 61, 62, 63, 64, 65, 66. For this purpose commercial drawingprograms can be used, such as for example Adobe-Illustrator,Macromedia-Freehand, Corel-Draw or the like. Contour lines 9 or gratingfields 6, 61, 62, 63, 64, 65, 66, which are to be filled with differentgrating patterns, are created preferably separately, e.g. in differentlevels of the drawing program or in different files. So as to increasethe clarity of the drawing indicated by the contour lines 9, areaslocated within the contour lines 9 can be differently coloured in thedrawing program.

In a further procedure step in the drawing program a grating pattern 10is produced, such as for example shown in FIG. 5. In FIG. 5 the gratingpattern 10 is composed of a multitude of hatching lines 11, whichcorrespond to the future grating lines. Since commonly used drawingprograms do not work in the micrometer range or therebelow and thedistance between the real grating lines typically lies within a range ofbetween 0,5 and 2 micrometer, the grating pattern 10 is drawn in ahighly magnified fashion. The magnification can be for example 10-fold,100-fold or 1000-fold. The grating pattern 10 created in such a way whenshown as computer image looks like a hatching, which extends across adrawing area 12.

But the grating pattern can also consist of wave-shaped or anyother-shaped grating lines. In the drawing program these grating lines,as mentioned above, are described, for example, as polygonal curves orBezier curves.

Then according to FIG. 6 tools of the drawing program are applied, whichpermit a linking of the contour line 9, produced in the first procedurestep and magnified with the same factor as the grating pattern, with thegrating pattern 10 in such a way, that the grating pattern 10 is onlypreserved within the contour lines 9.

Thereby the grating lines 13 shown in FIG. 7 are formed, which each aredefined by a starting point 14 and an end point 15, i.e. theintersection points the grating lines 13 have with the contour line 9,and together constitute a grating field 16. It has to be taken intoaccount, that in so far as possible only the grating lines 13 are leftover and all contour lines 9 are removed.

The data file of the drawing program then is converted into aconventional object-oriented format, in which segments of straight linesare described by their starting points and end points. Each grating line13 then is described by a starting point 14 and an end point 15. Asuitable object-oriented format is e.g. the EPS-(EncapsulatedPostscript) format.

In the event that the grating lines are not straight, the method is thesame. For a clear characterization of those sections of the gratingpattern located within the contour line 9, however, the intersectionpoints alone are not sufficient. The mathematical functions describingthe grating lines have to be taken into consideration here.

If the drawing program does not contain any tools for linking thegrating pattern 10 to the contour line 9, the following method can beapplied:

In a self-written program, e.g. in Visual C++, the hatching lines 11 areproduced with the desired spacing and in the desired angle ofinclination. The contour line 9 is read from an EPS format data fileinto the self-written program as a polygonal curve. The intersectionpoints the hatching lines 11 have with the contour line 9 are thestarting points 14 and end points 15 of the grating lines 13, which arerequired for the following procedure steps.

The EPS format data file containing the object data of starting points14 and end points 15 then has to be edited. In detail, the objects ofthe starting points 14 and end points 15 have to be brought to the rightscale and disposed in a suitable order.

With a suitable search program the object data of the starting points 14and end points 15 can be found in the EPS format data file. Here, ingeneral, one will notice, that the object data are stored in a ratherdisordered fashion. Therefore, one writes a program, which for eachstarting point 14 or end point 15 of a grating line 13 finds the mostproximate starting point 14 or end point 15 of a further grating line 13and sorts the grating lines in this order. If in every second gratingline 13 the starting point 14 and end point 15 are interchanged, then ameandering processing path 17 as shown in FIG. 8 will be the result.Since the grating lines 13 are connected to each other in a meanderingfashion by the idle distances 18 drawn in dashed lines.

Furthermore, the object data of the starting points 14 and end points 15are brought to the desired scale. If, for example, during the drawingprocess the values were magnified by a factor 1000, one interprets themillimeter values of the data record as micrometer values.

Data records are provided, which consist solely of starting points 14and end points 15 of the grating lines 13. The grating lines 13 are tobe written in an electron beam lithography machine, which works in aso-called CPC (Continuous Path Control) mode. This is a mode, in whichthe grating lines 13 characterized by starting points 14 and end points15 can be written in a continuous fashion, in contrast to the so called“stitching” that is mostly used, in which all image components, i.e. thelines as well, are divided into small elements.

As a substrate, e.g. a quartz glass plate can be used, which is providedwith a thin chromium layer and onto which a photoresist layer isapplied. The photoresist layer is of a thickness as required by thedesired depth of the image relief. Preferably the thickness of thephotoresist layer amounts to some 100 nanometer. The substrate and thecreated data records are supplied to the electron beam lithographymachine and the lithography process is started. Having worked throughall data records of the grating image, the substrate is removed from themachine and the photoresist layer is developed. The final result is thedesired grating image on the quartz glass plate in the form of apeak-and-valley profile.

The photoresist master then is further processed as usual in opticalholography. At first a thin silver layer is applied to the photoresistlayer by vapour deposition or chemical deposit. Then in a galvanic batha nickel molding of the photoresist master is produced, multiplied andused as embossing die for embossing an embossed layer. A grating image19 embossed in such a way is shown in FIG. 9. Therein the depressions 20in the embossed layer are shown by way of dark lines. Depending on theproduction method the dark lines can also represent raised areas. Thecompletely embossed embossed layer in the end is transferred to thefinal substrate, e.g. a bank note, credit card, or packaging material.The embossed layer here either is located on the final substrate orforms this substrate. This can be the case, for example, with foils,which later are cut into ID cards, bank notes, or security elements,such as security threads or labels. Alternatively, the embossed layercan be disposed on an intermediate carrier, such as a transfer material.Preferably the transfer material is a hot stamping foil. In the simplestcase it consists of a carrier foil, onto which a thermoplastic layer ora lacquer layer, preferably a UV curable lacquer layer is applied. Thegrating image is transferred into this lacquer layer or thermoplasticlayer with the help of the inventive embossing die. Then the embossedlayer is provided with a metallic or dielectric layer, which ensures,that the grating image can be viewed in reflected light. Then the layerstructure is provided with an adhesive layer, which when transferred isbrought into contact with the end substrate or an object to be secured.After the transfer the carrier foil preferably is stripped off.

All embodiments of the security element, security document, securitypaper or other objects to be secured can have further security featuresapart from the inventive grating image, such as machine-readable layersor other visually testable features.

The meandering processing path 17 shown in FIG. 8 in general ispreferred to a natural processing path 21 which runs in zigzag as shownin FIG. 10. In particular the idle distances, along which the electronbeam is inactive, are optimally shortened with the meandering processingpath 17. However, occasionally, the natural processing path shown inFIG. 10 can be of advantage as well, when, for example, the writingapparatus has to be turned off for cooling purposes between two writingoperations. Since the natural processing path 21 in zigzag form includeslong idle distances 22, the writing apparatus can be turned off whiletravelling along the idle distances 22.

A further advantage of the meandering processing path 17 is the factthat along the short idle distances 18 at the edge of the grating field16 the electron beam does not have to be deactivated, because the shortconnecting sections 23 at the edge of the grating field 16 do not affectthe optical function of the grating field 16. Therefore, with theelectron beam also the processing path 17 as shown in FIG. 11 in theform of a to a large extent continuous polygonal curve can be written.

For further increasing the writing speed the corners of the connectingsections 23 can be looped or rounded. A processing path 17 respectivelymodified is shown in FIG. 12.

The FIGS. 13 and 14 are to be understood analogous with FIGS. 6 and 7,wherein the grating pattern 30 overlapped with the contour line 9 doesnot consist of straight lines 11, but of wave-shaped grating lines 31.The grating lines 31 of the grating pattern 30 moreover are disposed insuch a way, that the spacing of the grating is increasing along agrating line 31 from the left to the right, as apparent in FIG. 13. Thegrating pattern 30 or the individual grating lines 31 here aredescribed, as explained above, by polygonal curves or Bezier curves.

Analogous with the method explained in connection with FIGS. 6 and 7,here too, the intersection points 32, 33, the individual grating lines31 have with the contour line 9, are determined. In contrast to thestraight grating lines, these intersection points 32 and 33 are notsufficient as to completely describe the grating lines 31. The datarecord for this grating field, therefore, contains apart from thecoordinates of the intersection points 32 and 33 also coordinates ofseveral or many intermediate points within the contour line 9.

It is pointed out, that the Figures are of a mere schematic nature andonly serve for illustrating. In practice the contour lines or the extentof the grating fields lie within the millimeter and centimeter range.The spacings between the grating lines lie in the micrometer range andtherebelow. I.e., when in the Figures only few grating lines are drawn,in practice this corresponds to up to several thousands of gratinglines. The electron beam as a lithography instrument permits very fineresolutions, which reach the nanometer range. For this reason it ispreferably used. In case gratings are to be written, which do notrequire such a high resolution, also other lithography instruments arepossible as to form the grating lines 13 in a substrate. Possiblemethods are mechanical engraving with a precision milling apparatus oranother form of material removal, e.g. with a focussed UV laser. Inprinciple all instruments can be used, which permit a writing of lines,on the basis of the above-mentioned data records, each starting at astarting point and ending at an end point, in a sufficiently fine linethickness onto a suitable substrate. Such a series of materialprocessing leaves characteristic marks in the substrate, due to whichthe person skilled in the art at least with the help of an electronmicroscope can recognize, which type of instrument was used forproducing the lines in the substrate.

1. Method for producing a grating image, which at least has one gratingfield, comprising the following steps: defining a contour line of thegrating field, filling the contour line with the grating pattern, thegrating pattern within the contour line being described by gratingcoordinates, supplying the grating coordinates to a writing apparatusand producing the grating pattern in a substrate with the writingapparatus and with the help of the grating coordinates.
 2. Methodaccording to claim 1, characterized in that the grating pattern isformed by grating lines which are disposed side by side.
 3. Methodaccording to claim 2, characterized in that as grating coordinates areselected the intersection points, the grating lines have with thecontour line, lying within the contour line.
 4. Method according toclaim 1, characterized in that with the help of a data processing systemthe contour line of the grating field is created and filled with thegrating pattern.
 5. Method according to claim 1, characterized in thatthe grating lines are straight or curved.
 6. Method according to claim1, characterized in that the grating coordinates of the grating linesare sequentially sorted according to their spatial disposition. 7.Method according to claim 6, characterized in that the coordinates of astarting point of a grating line rare sorted side by side with therespective coordinates of a starting point of a neighboring grating lineand the coordinates of an end point of a grating line side by side withthe respective coordinates of an end point of a further neighboringgrating line.
 8. Method according to claim 7, characterized in that thestarting points and end points of grating lines located side by side areconnected to form a meandering processing path.
 9. Method according toclaim 1, characterized in that the writing apparatus with the help ofradiation causes a change of state in a radiation-sensitive material.10. Method according to claim 9, characterized in that the writingapparatus is guided over the radiation-sensitive material according tothe grating coordinates.
 11. Method according to claim 9, characterizedin that as a radiation-sensitive material a photoresist layer appliedonto a substrate plate is used.
 12. Method according to claim 1,characterized in that as a writing apparatus an electron beam is used.13. Method according to claim 9, characterized in that after the causedchange of state a metallization layer is applied onto theradiation-sensitive material and that therefrom a metallic molding isgalvanically produced.
 14. Method according to claim 13, characterizedin that the molding is used as an embossing die for embossing a gratingimage into a substrate.
 15. Grating image, which has at least one imagefield separately perceptible with the naked eye, in which a gratingpattern consisting of not interrupted grating lines is disposed, whichis produced by means of a lithography instrument.
 16. Grating imageaccording to claim 15, characterized in that as a lithography instrumentfocussed light radiation or a focussed particle beam, is used. 17.Grating image according to claim 15, characterized in that the gratingimage has several image fields.
 18. Grating image according to claim 15,characterized in that the grating image has further image parts, whichare manufactured with the help of a different technique.
 19. Gratingimage, according to claim 15, characterized in that the grating patterncomprises grating lines, which form a diffraction grating.
 20. Gratingimage according to claim 15, characterized in that the grating lines areconnected to at least one meandering grating line by reversing sectionsdisposed at their ends.
 21. Grating image according to claim 15,characterized in that the reversing distances are rounded.
 22. Securityelement with a grating image according to claim
 15. 23. Security elementaccording to claim 22, characterized in that the security element is asecurity thread, a label or a transfer element.
 24. Security paper witha grating image according to claim
 15. 25. Security paper with asecurity element according to claim
 22. 26. Security document with agrating image according to claim
 15. 27. Security document with asecurity element according to claim
 22. 28. Security document with asecurity paper according to claim
 24. 29. Transfer material with agrating image according to claim
 15. 30. Apparatus for producing agrating image, which at least has one grating field perceptible with thenaked eye, comprising the following devices: device for defining acontour line of the grating field, device for filling the contour linewith a grating pattern, the grating pattern being described within thecontour line by grating coordinates, device for supplying the gratingcoordinates to a writing apparatus, writing apparatus for producing thegrating pattern in a substrate with the help of the grating coordinates.31. Apparatus according to claim 30, characterized in that the writingapparatus is an electron beam.
 32. The method of claim 3 wherein thegrating points of the grating field lie within the contour line.
 33. Thegrating image of claim 16 wherein said particle beam is an electronbeam.
 34. A security paper with a security element according to claim23.
 35. A security document with a security element according to claim23.
 36. A security document with a security paper according to claim 25.37. The transfer material of claim 29, comprising hot stamping foil.